As is known, materials based on lignocellulosic materials, in particular timber-based materials, are at risk from attack by harmful insects, for example wood-destroying beetles, ants and/or termites. Since attack can lead to damage and, in extreme cases, to complete destruction of the material, a great deal of effort goes into protecting such materials against such an attack.
Traditional timber preservatives which are based on tar oils, such as carbolineum, are not very attractive because of their intrinsic odor and the possibility of being carcinogens. This is why defined organic active ingredients are nowadays being employed for this purpose. Since these active ingredients are usually substances which are insoluble in water, they are, as a rule, formulated as solutions in organic solvents (see Ullmann's Encyclopedia of E. H. Pommer, “Wood, Preservation” Chapter 2, in Ullmann's Encyclopedia of Industrial Chemistry, 5th ed. on CD-ROM, Wiley-VCH Weinheim 1997). However, the use of solvents entails additional costs and moreover undesired for reasons of work hygiene and for environmental reasons. Moreover, there is the risk of the active ingredients being leached under atmospheric influences so that the resistance to atmospheric corrosion of such insecticidal finishes is frequently not satisfactory.
U.S. Pat. No. 3,400,093 discloses aqueous, insecticide-comprising polymer dispersions which are prepared by emulsion polymerization of ethylenically unsaturated monomers, where the monomers employed for the polymerization comprise a dissolved water-insoluble insecticidal active ingredient. The insecticide-comprising polymer dispersions described therein are employed for the preparation of water-based coating compositions such as dispersion paints and are intended to ensure an insecticidal finish of the coating. These polymer dispersions, however, are not suitable for the protection of timber.
The earlier German patent application 102004020332.6 describes aqueous active ingredient preparation comprising at least one fungicidal organic active ingredient with a solubility in water of not more than 5 g/l at 25° C. at 1013 mbar and a finely divided polymer with a mean particle size, determined by dynamic light scattering, of not more than 300 nm, where the polymer particles of the finely divided polymer comprise the active ingredient and where the polymer consists predominantly of ethylenically unsaturated monomers with a solubility in water or not more than 30 g/l at 25° C. These active ingredient compositions are suitable for protecting timber against wood-damaging fungi.
The earlier German patent application 102004037850.9 describes aqueous active ingredient compositions comprising at least one organic crop protectant, for example an insecticidal, fungicidal, acaricidal or herbicidal active ingredient, with a solubility in water of not more than 5 g/l at 25° C. at 1013 mbar and a finely divided polymer, where the active ingredient compositions are obtainable by a multi-step emulsion polymerization method in an aqueous suspension of the solid active ingredient particles, where the active ingredient particles in the suspension have a mean particle size, determined by dynamic light scattering, of not more than 1200 nm. This gives polymer/active ingredient particles in which the particle-shaped active ingredient is present in a form where it is coated by the emulsion polymer.